Pipe-bending machine.



J. FRANK.

PIPE BENDING MACHINE.

APPLICATION FILED owe. 1911.

1,293,397. Patented Feb. 4,1919.

2 SHEETSSHEET I.

/ r TOR/V5145 J1 FRANK.

PIPE BENDING MACHINE.

APPLICATION FILED 0Ec.8. l9n.

1,293,397, 5 Patented Feb. 4, 1919.

2 SHEETSSHEET 2- 1s Putts m, rnmmna, wuumnan. n

both sides. :roller or stationary friction surface is not UNITED STATES PATENT orrrcn.

JOS EIPH FRANK, OF CHICAGO, ILLINOIS.

PIPE-BENDING MACHINE.

Specification of Letters Patent.

PatcntedFeb. a, 1919.

Application filed December 8, 1917. Serial No. 206,213.

To all whom it may concern:

Be it known that I, J OSEPH FRANK, a Cltl-t zen of the United States, residing at Chi- :cago, in the county of Cook and State of Illinois, have invented new and useful Im-' provements. in Pipe-Bending Machines, of

which the following is a specification. V Y My invention is concerned with tube bending machines of the character used in forming the crooks in brass band instruments, and it is designed to produce a machine of the class described which shall be simpler in its construction and more efficient in its operation than imilar machines which have heretofore been employed.

In another aspect, it: is concerned with a I machine of the class described which can be readily changed to adapt it i for making crooks of different radii.

As 'such devices have been constructed prior to myinvention, where a mandrel has been employed to cooperate with the interior of the tube and bend it around the curved form, it has been considered-necessary to employ either a roller or a stationary friction surface which shall engage with the tube on the convex side of-the curve, and thus squeeze the tube against the mandrel on I have found that this outside essential, andis in fact detrimental as it produces unnecessary deformation of the surface of the tube with which it engages,

as well as usesup unnecessary power in squeezing the material of thetube between it andthe mandrel, and furthermore it limits the form of the curve to the arc of a true I circle. By my novel construction in which this roller or friction surface is omitted, I

secure a better product in the finished tube,

I operate the apparatus with less'power, and as the mandrel can give a little toward its free end, I am enabled within certain limits to form a curve that is not the arc of a true circle. This same omission ofthe outside roller or friction surface enables me within certain limits to make curves of different radii by merely changing the size of the To illustrate myinvention I annex hereto forms and the angle at which the clamping mechanism stands. a

' two sheets of drawing in which the same reference characters are used to designate line adjustment shows it arranged for the curve of an intermediate radius.

' For carrying out my invention in its simplest and preferred form, -I employ a base plate 5, preferably formed of heavy metal and secured upon a work bench or supported in any desired manner. Projecting upward from and rigidly secured to this base plate is the bearing stud 6, which preferably has the reduced portion forming a shoulder 12 upon which is fulcrumed the operating lever 7 which is conveniently detachably secured in place by the nut 11 on the threaded upper end of the stud 6. The

stud has loosely mounted thereon one of the circular form 9, of which I may employ three for instance, as illustrated in Figs. 3 and l by the forms 9, 9? and 9 which are progressive by decreasing diameters, as

shown, to make tubes having correspondingly decreasing radii. Each of these forms 9 has in the periphery thereof an annular groove 10, semi circular in cross section, and of the proper dimensions to correspond with the cross-section of the particular side of the tube with which it is used.

-To hold the tube being operated on, I employ clamping mechanism, preferably such as illustrated, which consists of a block 18 having a the same shape and dimensions as the groove 10. Associated with the fixed clamping member 13 is a movable member 15, of the same general construction, but-smaller, having formed in its adjacent surface the similar groove 16, and adapted to be forced toward the fixed clamping member-13 to grip the tube to be'bent between the two blocks by the eccentric stud 17 which is mounted to oove 14 in the face thereof adjacent to t e form 9, which groove 14 is of rotate in the base 5, as seen in Fig. 2, and which is moved by the arm 25 placed in the top thereof. To make the stationary clamping block 13 adjustable so that it can be used with the forms 9, 9 and 9 of different diameter, as shown in Figs. 3 and i, I provide it with a pair of vertical longitudinal. slots 19 formed therein, through which slots extend upward the bolts 18 which have their lower ends secured or fixed in the base 5, and by the employment of nuts on the upper ends of the bolts 18 I am able to place the block 13 in either one of the three positions shown in Figs. 3 and 4 and rigidly secure it in either one of these positions.

The mandrel 20, which is a steel rod of the proper diameter to readily enter the tube to be bent with its outer end filling the tube, is supported in the horizontal plane of the grooves 10, 1d and 16 by the arm 21 secured to the lever 7 and having its outer end 22 bent down at right angles and provided with an aperture through which the adjacent threaded end of the mandrel 20 is passed and secured rigidly in position by the nuts and look nuts 23 and 23. A scallop 2-1- is formed in the arm 21 to permit the lever to be swung as far as is necessaryto make a bend of 180 degrees in a tube without its being interrupted by the arm 21 engaging the eccentric stud 17.

The operation of the device will now be readily apparent: With the parts in the position shown in Fig. 3, for instance, but with the eccentric 17 turned to allow the movable block'15 to be-moved away from tlwblock 13, the tube to be bent "is thrust between the grooves 14% and 16 and over the end of the mandrel 20 and shoved onto the mandrel as far as necessary to make the length of curve contemplated. The eccentric 17 is then swung around to force the block '15 toward the block 13, thereby clamping the "tube securely in position and the lever 7 is then swung anti-clockwise with the result that the end of the mandrel 20 is drawn out of; the tube, and as it is drawn out, it bends the portion ofthe tube which it isleavin g around'the form 9, leaving the tube a perfect circle in cross-section while at the same time bending it into the shape of the formQ. The mandrel '20 can spring enough to accommodate it to the different sized forms 9, 9 and '9" which will be changed as desired, and if 'a form employing a curve which is not a true circle should beemp'loyed the-spring of the mandrel 20 will be-su'fiicient'to allow it to accommodate itself to the dorm ofthe curve and operate justthesame as if the form were curvedon the arc of a =-true circle. I

While {I have shown and described my invention as embodied inthe form which I at present consider best adapted to carry out its purposes, it will be understood that it is capable of modifications, and that I do not desire to be limited in the interpretation of the following claims except as may be necessitated by the state of the prior art.

Whatl claim as new and desire to secure by Letters Patent inthe United States is:

1. In a tube bending machine, the combination with a base adapted to have any one of a plurality of circular forms of diflerent diameters secured on said base at the samecentrahpointfso as to produce curved tubes of different radii of curvature on the same machine, of one of said circular forms, 11 operating lever pivoted co-aXially wi-t-h the form, a single stationary clamping member detached from the term and adjustable on the base to bring its tube engaging jaw with its axis tangentialtothe circular'form irrespective of its diameter, means for securing the clamping nember to-the base in any adjustment, a-mova'ble "clamping member cooperating with the stationary clamping member to hold the tube, amandrel supported at its outer end only by the lever so as to be free to spring and adapted to have the free inner end enter a-tub'e held in the clamping members .and tangentially to the form, and means for holding the movable clampingfinemberin position to cooperate with the stationary clamping member.

2. In a tube bending machine, the'cornbination with a base, of a vertical bearing stud projecting upwardly therefrom adapted to have one ota plurality of-annular forms of di'ii'erent external diameters but having the same internal diameter fit snugly thereon and resting on the base so as to produce curved tubes of difl'erent radii of curvature on the same machine, one of said annular forms,- an operating lever pivoted on the stud, a single stationary clamping member detached "from the form and adjustable onthe base to bring its tube engaging jaw with its axis tangential to the form irrespective of its diameter, means for securing the clamping member to the base in any adjustment, 'a movable clamping member cooperating with the stationary clamping member to hold the tube, a mandrel supported at its outer end only by the operating lever so as to be free-to-spring and adapted to have its freeinner end enter a tube held in the clamping members and tangentially to the form, "and r neans for holdingthe ovable clamping member in position to cooperate with the stationary clamping member.

"3, Ina tube bending machine, the combination with a base, or a vertical stud secured therein and projecting upward "therefrom adapted to have one "of a plurality of annular forms of different externaldiameters but having the same internal diameter so as to produce curved tubes of different fitted snugly thereon and rest. on the base radii of curvature on the same machine, one of said forms, an operating lever fulcrumed on the stud, a single stationary clamping member detached from the form and havlng two elongated slots therein extending substantially at right angles to the jaw thereof adjustable on the base to bring its tube engaging jaw with its axis tangential to the annular form irrespective of its diameter, bolts secured to the base extending through the slots in the form and provided with nuts, a movable clamping member cooperat- Copies of this patent may be obtained for five cents each, by addressing the Commissioner 'of Patents,

ing with the stationary clamping member to hold the tube, a mandrel supported at its outer end only by the operating lever so as to be free to spring and adapted to have its free inner end enter a tube held by the clamping members and tangentially to the form, and an eccentric for holding the movable clamping member in position to cooperate with the stationary clamping member.

In testimony whereof I affix my signature.

JOSEPH FRANK.

wtlhlngton, D. G. 

